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According to one embodiment, a seating detection sensor includes a strain
generating body and a strain gauge. The strain generating body is held on
a casing or a toilet seat. The strain generating body receives a load
from the toilet seat via a shaft portion to generate a strain. The strain
gauge is provided on the strain generating body and detects a strain
amount of the strain generating body. A force release portion releases a
force applied to an opening in a horizontal direction from the shaft
portion in a state of the shaft portion abutting the opening so that the
force is not converted downwardly in a vertical direction.

1. A toilet apparatus comprising: a casing; a toilet seat attached
rotatably to the casing, an opening being provided on one of the casing
or the toilet seat, a shaft portion being provided on one other of the
casing or the toilet seat, the shaft portion being inserted into the
opening, the shaft portion being capable of abutting the opening by
movement of the toilet seat in a front-back direction; a seating
detection sensor detecting seating of an user on the toilet seat, the
seating detection sensor including a strain generating body and a strain
gauge, the strain generating body being held on the casing or the toilet
seat, the strain generating body receiving a load from the toilet seat
via the shaft portion to generate a strain, the strain gauge being
provided on the strain generating body and detecting a strain amount of
the strain generating body; and a force release portion releasing a force
applied to the opening in a horizontal direction from the shaft portion
in a state of the shaft portion abutting the opening so that the force is
not converted downwardly in a vertical direction.

2. The toilet apparatus according to claim 1, wherein the opening is
provided in the casing, the shaft portion is provided in the toilet seat,
and the strain generating body is held to the casing below the shaft
portion.

3. The toilet apparatus according to claim 1, wherein the force release
portion maintains a force applied from the shaft portion to the strain
generating body in a vertical direction in a state of the shaft portion
not abutting the opening also in a state of the shaft portion abutting
the opening.

4. The toilet apparatus according to claim 2, wherein the force release
portion maintains a force applied from the shaft portion to the strain
generating body in a vertical direction in a state of the shaft portion
not abutting the opening also in a state of the shaft portion abutting
the opening.

5. The toilet apparatus according to claim 3, wherein the force release
portion is a vertical surface of the opening, the shaft portion being
capable of abutting the vertical surface.

6. The toilet apparatus according to claim 4, wherein the force release
portion is a vertical surface of the opening, the shaft portion being
capable of abutting the vertical surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priority
from Japanese Patent Application No. 2016-188653, filed on Sep. 27, 2016;
the entire contents of which are incorporated herein by reference.

FIELD

[0002] Embodiments described herein relate generally to a toilet
apparatus.

BACKGROUND

[0003] At the present time, a toilet apparatus including seating detection
function using a micro switch is released. In the configuration based on
the micro switch like this, a user feels strange by sinking the toilet
seat when seated, and it sounds like a clicking sound with a small
volume, and then quality of level is left to be improved.

[0004] Here, it is conceived that seating detection is performed by using
a strain gauge. For example, JP H06-88371 A (Kokai) discloses the
configuration where the strain gauge is attached to a back surface of the
toilet seat, a hinge portion or the like. JP 2000-254040 A (Kokai)
discloses the configuration where a load detection means formed of a
strain gauge is provided in the toilet seat.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1A is a top view of a toilet apparatus of an embodiment, and
FIG. 1B is an enlarged view of a state in which a toilet seat is removed
in portion A of FIG. 1A;

[0006] FIG. 2 is a perspective view of a portion shown in FIG. 1B as
viewed from right side;

[0007] FIG. 3 is an A-A cross sectional view in FIG. 1B;

[0008] FIG. 4 is an enlarged view of a portion B in FIG. 3;

[0009] FIG. 5 is a B-B cross sectional view in FIG. 1B;

[0010] FIG. 6A is an enlarged view of an opening formation portion in a
casing of the embodiment, and FIG. 6B shows insertion of a shaft portion
of the toilet seat into the opening of FIG. 6A;

[0011] FIGS. 7A and 7B are perspective views of a position shift
absorption member of the embodiment;

[0012] FIG. 8 is a perspective view of the position shift absorption
member, a strain generating body, and a strain gauge of the embodiment;

[0013] FIG. 9 is a circuit block diagram of the toilet apparatus of the
embodiment;

[0014] FIG. 10A is a view similar to FIG. 4 showing a hinge portion of the
embodiment, and FIGS. 10B and 10C are views of comparison examples to
FIG. 10A;

[0015] FIGS. 11A and 11B are schematic views showing movement in a
front-back direction of a user seating on the toilet seat;

[0016] FIGS. 12A to 12C are schematic views showing other examples of the
opening formed in the casing of the embodiment; and

[0017] FIG. 13A is a schematic cross sectional view along a vertical
direction of a hinge portion of other embodiment, and FIG. 13B is a
partial cross sectional side view as viewing a left side to a D-D line in
FIG. 13A.

DETAILED DESCRIPTION

[0018] The load applied to the toilet seat on user seating is easily
smaller than a back surface of the toilet seat in a hinge portion. If
seating is intended to detect by providing a strain gauge on the hinge
portion, when the same strain gauge and strain generating body are used,
the strain generating body is hard to deflect compared with the case of
providing the strain gauge on the back surface of the toilet seat, and
then the output of the strain gauge provided on the strain generating
body becomes small.

[0019] That is, since the output of the strain gauge provided on the hinge
portion is small, the load due to movement of the toilet seat in a
front-back direction accompanied with weight shift of the user influences
largely load detection in a vertical direction.

[0020] If it is conceived that the seating is intended to be detected in
various seating of various people, for example, it is desired that the
strain generating body is easy to be deflected so as to detect the
seating and the output of the strain gauge is made large even if a child
sits on a front of the toilet seat, however on the other hand, there is a
fear that when a grown-up shifts the weight on the toilet seat, the
strain generating body is broken by a larger load applied to the strain
generating body than expected.

[0021] A toilet apparatus of a first invention comprising: a casing; a
toilet seat attached rotatably to the casing, an opening being provided
on one of the casing or the toilet seat, a shaft portion being provided
on one other of the casing or the toilet seat, the shaft portion being
inserted into the opening, the shaft portion being capable of abutting
the opening by movement of the toilet seat in a front-back direction; a
seating detection sensor detecting seating of an user on the toilet seat,
the seating detection sensor including a strain generating body and a
strain gauge, the strain generating body being held on the casing or the
toilet seat, the strain generating body receiving a load from the toilet
seat via the shaft portion to generate a strain, the strain gauge being
provided on the strain generating body and detecting a strain amount of
the strain generating body; and a force release portion releasing a force
applied to the opening in a horizontal direction from the shaft portion
in a state of the shaft portion abutting the opening so that the force is
not converted downwardly in a vertical direction.

[0022] According to the first invention, the load applied in the vertical
direction to the strain generating body when the user seats on the toilet
seat is not influenced by the load due to the weight shift or the like of
the user, and since the original vertical load is surely applied to the
strain generating body, it is possible to detect surely seating of the
user on the toilet seat. Since there is no conversion from the horizontal
load to the vertical load, the excessive load is not applied to the
strain generating body, and it is possible to prevent the breakage of the
strain generating body and the strain gauge.

[0023] According to a toilet apparatus of a second invention, the opening
is provided in the casing, the shaft portion is provided in the toilet
seat, and the strain generating body is held to the casing below the
shaft portion.

[0024] According to the second invention, it is possible to provide the
seating detection sensor on the hinge portion without changing the
existing configuration largely.

[0025] According to a toilet apparatus of a third or fourth invention, the
force release portion maintains a force applied from the shaft portion to
the strain generating body in a vertical direction in a state of the
shaft portion not abutting the opening also in a state of the shaft
portion abutting the opening.

[0026] According to the third or fourth invention, it is possible to
eliminate almost no noise of the vertical load applied to the strain
generating body, and setting of correlation between the load applied to
the strain generating body and the output of the strain gauge becomes
easy.

[0027] According to a toilet apparatus of a fifth or sixth invention, the
force release portion is a vertical surface of the opening, the shaft
portion being capable of abutting the vertical surface.

[0028] According to the fifth or sixth invention, even if the shaft
portion abuts the side face (vertical surface), the shat portion receives
just only a reaction force in the horizontal direction from the opening,
and does not receives the force in the vertical direction. Therefore, the
force applied in the vertical direction to the strain generating body
from the shaft portion in a state of the shaft portion not abutting the
side face of the opening does not change also in a state of the shaft
portion abutting the side face of the opening, and is maintained.

[0029] According to the invention, it is possible to improve a seating
detection performance against a small load and to prevent breakage of the
strain generating body and the strain gauge due to a large load while
improving a quality by providing the seating detection sensor using the
strain gauge at the hinge portion.

[0030] Various embodiments will be described hereinafter with reference to
the accompanying drawings. The same numerals are applied to similar
constituent elements in the drawings.

[0031] FIG. 1A is a top view of a toilet apparatus 10 of an embodiment.

[0032] The toilet apparatus 10 of the embodiment includes a casing 11 and
a toilet seat 15. The toilet seat 15 includes a toilet seat main part 16,
and a pair of shaft portions (rotation shaft) 17 provided near left and
right ends in a width direction at a rear end portion of the toilet seat
main part 16.

[0033] The shaft portion 17 of the toilet seat 15 is inserted into an
opening described later and formed in the casing 11, and the toilet seat
15 is rotatably attached to the casing 11 using the shaft portion 17 as a
fulcrum. In the toilet apparatus 10 of the embodiment, a portion serving
as a fulcrum of rotation of the toilet seat 15 is referred to as a hinge
portion as well.

[0034] FIG. 1B is an enlarged view of a portion (portion A of FIG. 1A)
provided with one hinge portion in a pair of hinge portions. FIG. 1B
shows state in which the toilet seat main part 16 is removed.

[0035] The one hinge portion shown in FIG. 1B is provided with a seating
detection sensor as described later. The other hinge portion is not
provided with the seating detection sensor. Or the seating detection
sensor may be provided in the other seating detection sensor. The seating
detection sensor may be provided in at least one of the two hinge
portions.

[0036] FIG. 2 is a perspective view of a portion shown in FIG. 1B as
viewed from right side.

[0040] FIG. 6A is an enlarged view of an opening formation portion in the
casing 11, and FIG. 6B shows insertion of shaft portion 17 of the toilet
seat 15 into an opening 20 of FIG. 6A.

[0041] As shown in FIG. 6A, the opening 20 is formed on a side face 12 of
the casing 11. In FIGS. 6A and 6B, the left side shows the front of the
toilet apparatus 10, the right side shows the rear of the toilet
apparatus 10, and the lower side shows a direction of action of gravity.

[0042] A side face 21 on the front side and a side face 21 on the rear
side in the opening 20 of the toilet apparatus are a vertical surface
extending in the vertical direction. A face 22 on the upper side and a
face 23 on the lower side to the side face (vertical surface) 21 in the
opening are curved surfaces. The side face 21, the face 22 on the upper
side, and the face 23 on the lower side are continuously formed and form
a contour of the opening 20.

[0043] The face 22 on the upper side is an upwardly convex curved surface,
and the face 23 on the lower side is a downwardly convex curved surface.
A distance along a horizontal direction between a pair of side faces 21
is shorter than a distance along the vertical direction between a top of
the face 22 on the upper side and a bottom of the face 23 on the lower
side.

[0044] AS shown in FIG. 4, FIG. 5, and FIG. 6B, the shaft portion 17 of
the toilet seat 15 is formed cylindrically, and the shaft portion 17 is
inserted inside the casing 11 through the opening 20. A clearance
tolerating rotation of the shaft portion 17 is formed between an outer
circumferential surface of the shaft portion 17 and an inner surface of
the opening 20 (side face 21, face 22 on the upper side, and the face 23
on the lower side).

[0045] For the clearance, the toilet seat 15 is slightly movable in the
front-back direction (horizontal direction in FIG. 6B) of the toilet
apparatus 10. Since the shaft portion 17 abuts the side face 21 of the
opening 17, the toilet seat 15 is regulated to move more in the
front-back direction.

[0046] Inside the casing 11, a position shift absorption member 30 is
provided in the portion where the shaft portion 17 of the toilet set 15
is inserted, as shown in FIG. 4, FIG. 5.

[0047] FIG. 7A is a perspective view of the position shift absorption
member 30, and FIG. 7B is a perspective view of the position shift
absorption member 30 as viewed from the opposite side to FIG. 7A.

[0048] The position shift absorption member 30 includes a tubular portion
31 and a push portion 36, and these are provided integrally. Furthermore,
a regulation means 40 is integrally provided with the position shift
absorption member 30. The regulation means 40 may be another body to the
position shift absorption member 30.

[0049] A load receiver 35 is provided in a lower portion in the vertical
direction of the tubular portion 31. A portion of an inner
circumferential surface of the tubular portion 31 is a horizontal
surface, and the horizontal surface serves as the load receiver 35. An
opening 32 is formed on one side in an axis direction of the tubular
portion 31, and a cover 33 is integrally provided on the other side.

[0050] The regulation means 40 is provided below the outside of the outer
circumferential surface of the tubular portion 31. The regulation means
40 includes an upper face portion 41, a side face portion 42, and a lower
face portion 43, and these are integrally provided in a quadrangle frame
shape. The lower face portion 43 is not continuous in the horizontal
direction, divided by a notch, and the side face portion 42 and the lower
face portion 43 are formed in an L-shape in the cross section.

[0051] The push portion 36 is provided on a back surface of the upper face
portion 41 below the load receiver 35. The push portion 36 is provided as
a protrusion portion projecting downward from the back surface of the
upper face portion 41, and extends in the axis direction of the tubular
portion 31.

[0052] As shown in FIGS. 6A and 6B, a holding portion 13 in a recessed
shape is provided below the opening 20 inside the side face 12 of the
casing 11. The holding portion 13 is integrally provided with the casing
11.

[0053] As shown in FIG. 5, the position shift absorption member 30 is
provided above the holding portion 13 inside the side face 12 of the
casing 11. As shown in FIG. 2, FIG. 4, the regulator means 40 is disposed
in the holding portion 13 in a recessed shape of the casing 11. The lower
face portion 43 of the regulator means 40 is on a bottom of the holding
portion 13, and the bottom of the holding portion 13 supports the
regulator means 40 and the position shift absorption member 30 in the
vertical direction.

[0054] The side face portion 42 of the regulator means 40 abuts the side
face of the holding portion 13, and thus the movement of the regulator
means 40 and the position shift absorption member 30 in the front-back
direction (horizontal direction in FIG. 4) of the toilet apparatus 10 is
regulated.

[0055] As shown in FIG. 5, the shaft portion 17 of the toilet seat 15 is
inserted inside the tubular portion 13 through the opening 20 of the
casing 11 and the opening 32 of the tubular portion 13 of the position
shift absorption member 30, and the shaft portion 17 is on the load
receiver 35 of the position shift absorption member 30.

[0056] In a state of the shaft portion 17 being on the load receiver 35,
the clearance is ensured between the shaft portion 17 and the face 23 on
the lower side of the opening 20 of the casing 11. That is, the load of
the toilet seat 15 in the vertical direction is not applied to the face
on the lower side of the opening 20 of the casing 11. The load receiver
35 of the position shift absorption member 30 receives the load of the
toilet seat 15 in the vertical direction via the shaft portion 17.

[0057] The cover 33 is provided on an opposite side of the opening 32 in
which the shaft portion 17 is inserted in the tubular portion 13 of the
position shift absorption member 30 as shown in FIG. 2, FIG. 5.

[0058] As shown in FIG. 4, a strain generating body 50 is held inside the
regulator means 40. The strain generating body 50 is sandwiched between
the push portion 36 of the position shift absorption member 30 and the
lower face portion 43 of the regulator means 40. A side face of the
strain generating body 50 abuts the side face portion 42 of the regulator
means 40, and the movement of the strain generating body 50 in the
front-back direction (horizontal direction in FIG. 4) is regulated. That
is, the relative shift in the front-back direction of the strain
generating body 50 to the push portion 36 is regulated.

[0059] The regulator means 40 is supported on the holding portion 13 of
the casing 11. Therefore, the strain generating body 50 held on the
regulator means 40 is held to the casing 11 below the shaft portion 17 of
the toilet seat 15.

[0060] The load receiver 35 is provided between the shaft portion 17 and
the strain generating body 50, and the shaft portion 17 is on the load
receiver 35 in contact with the load receiver 35. The push portion 36 is
provided between the load receiver 35 and the strain generating body 50.
The load receiver 35 receives the load of the toilet seat 15 via the
shaft portion 17, the load received by the load receiver 35 is
transmitted to the push portion 36, and the push portion 36 pushes the
strain generating body 50.

[0061] The strain generating body 50 is pushed by the push portion 36 to
be deflected, and the strain is generated in the strain generating body
50. The strain generating body 50 is made of a metal material, for
example, made of a stainless material. Or, the strain generating body 50
may be formed from a resin material.

[0062] FIG. 8 is a perspective view of the regulator means and the
position shift absorption member 30 in a state of holding the strain
generating body 50 as viewed from below.

[0063] As shown in FIG. 8, a stain gauge 60 detecting a strain amount of
the strain generating body 50 is provided on a back surface (lower face)
of the strain generating body 50. The strain gauge is formed in a region
not covered with the lower face portion 43 of the regulator means 40 in
the back surface of the strain generating body 50. The strain gauge 60
faces the bottom of the holding portion 13 shown in FIG. 4 via a space.

[0064] The strain generating body 50 and the strain gauge 60 form a
seating detection sensor detecting seating of the user on the toilet seat
15.

[0065] FIG. 9 is a circuit block diagram of the toilet apparatus 10 of the
embodiment.

[0066] The strain gauge 60 includes, for example, the configuration
forming a Wheatstone bridge circuit from a metal film patterned on a
resin film. When a force is applied to the strain generating body 50 and
the strain is generated in the strain generating body 50, a resistance
value of the strain gauge 60 changes and an output voltage of the
Wheatstone bridge circuit changes.

[0067] The output voltage of the Wheatstone bridge circuit is inputted to
a controller 90 via an amplifier 80, and the controller 90 controls
various instruments of the toilet apparatus 10 in response to presence or
absence of seating detection.

[0068] FIG. 10A is a view similar to FIG. 4 showing a hinge portion of the
embodiment, and FIG. 10B and FIG. 10C are views of comparison examples to
FIG. 10A.

[0069] The side face 21 of the opening 20 of the embodiment shown in FIG.
10A is a vertical surface as described before. In contrast, an opening
20' in FIGS. 10B and 10C of the comparison example has a perfect circular
shape, and the side face is a curve surface.

[0070] FIG. 11A shows a state in which a user 100 sits on the front of the
toilet seat 15. FIG. 11B shows a state in which the user 100 shown in
FIG. 11A shifts the weight to the rear side, and changes a sitting
position to the rear side of the toilet seat 15.

[0071] The weight shift like this to the rear side of the user 100 also
moves the shaft portion 17 of the toilet seat 15 to the rear side, the
shaft portion 17 being inserted to the openings 20, 20' of the casing 11.
FIG. 10A shows a state in which the shaft portion 17 abuts the side face
21 on the rear side in the opening 20 due to the movement of the shaft
portion 17 to the rear side, and FIG. 10B and FIG. 10C show a state in
which the shaft portion 17 abuts the inner circumferential surface on the
rear side in the opening 20' due to the movement of the shaft portion 17
to the rear side.

[0072] As shown in FIGS. 10B and 10C, if the shaft portion 17 abuts the
curved surface, a partial component of a horizontal load accompanied with
the movement of the shaft portion 17 to the rear side is converted to a
vertical load.

[0073] FIG. 10B shows an example in which the shaft portion 17 abuts a
portion on the lower side of a rear side inner circumferential surface in
the opening 20', and the partial component of the horizontal load is
converted to a vertically upward load. An upward force is applied to the
shaft portion 17 as a reaction from the opening 20'. For this reason, an
original vertically downward load A applied from the shaft portion 17 to
the strain generating body 50 via the load receiver 35 and the push
portion 36 is reduce by an upward load B (noise of vertical load)
converted from the horizontal load, and then a load C smaller than the
original vertically downward load A becomes a detected load. That is, the
strain amount of the strain generating body 50 decreases. This may lead
an incorrect detection result (decrease of detection ability) indicating
that despite the user is seated on the toilet seat 15, the user does not
seat from the reason that the output voltage of the strain gauge 50 does
not reach a seating detection voltage.

[0074] Conversely, FIG. 10C shows an example in which the shaft portion 17
abuts a portion on the upper side of a rear side inner circumferential
surface in the opening 20', and a partial component of the horizontal
load is converted to a vertically downward load. A downward force is
applied to the shaft portion 17 as a reaction from the opening 20'. For
this reason, a downward load B' (noise of vertical load) further
converted from the horizontal load is added to the original vertically
downward load A applied from the shaft portion 17 to the strain
generating body 50 via the load receiver 35 and the push portion 36. This
may lead breakage of the strain generating body 50 and the strain gauge
60 due to application of an excessive load C' exceeding a breakdown load
(breakdown limit) of the strain generating body 50 to the strain
generating body 50.

[0075] Also in the case where the toilet seat 15 moves to the front side
and the shaft portion 17 abuts a front side inner circumferential surface
of the opening 20', increase and decrease of the load to the original
vertical load may be caused by the horizontal load.

[0076] In contrast, according to the embodiment, when the shaft portion 17
abuts the opening 20 due to the movement of the toilet seat 15 in the
front-back direction, a force release portion is provided, which releases
a force (horizontal load) applied to the opening 20 from the shaft
portion 17 so that the force is not converted in the vertical direction.
This force release portion is specifically the side face 21 of the
opening 20 formed as the vertical surface.

[0077] The side face 21 in a region (range) which the shaft portion 17 in
the opening 20 is capable of abutting forms the vertical surface. For
that reason, even if the shaft portion 17 abuts the side face (vertical
surface) 21, the shat portion 17 receives just only a reaction force in
the horizontal direction from the opening 20, and does not receives the
force in the vertical direction. Therefore, the force applied in the
vertical direction to the strain generating body 50 from the shaft
portion 17 in a state of the shaft portion 17 not abutting the side face
21 of the opening 20 does not change also in a state of the shaft portion
17 abutting the side face 21 of the opening 20, and is maintained.

[0078] That is, the load A applied downwardly in the vertical direction to
the strain generating body 50 when the user seats on the toilet seat 15
is not influenced by the load due to the weight shift or the like of the
user, and since the original vertical load A is surely applied to the
strain generating body 50, it is possible to detect surely seating of the
user on the toilet seat 15. Since there is no conversion from the
horizontal load to the vertical load, the excessive load is not applied
to the strain generating body 50, and it is possible to prevent the
breakage of the strain generating body 50 and the strain gauge 60.

[0079] According to the embodiment configured like this, because the
seating detection sensor is provided on the hinge portion that the strain
amount of the strain generating body 50 is apt to be small, while the
strain generating body 50 is easy to be deflected so that even though the
seating of a small load can be detected, even though the horizontal load
is generated by the weight shift or the like of the user, the load is not
transmitted to the strain generating body 50, therefore it is possible to
prevent the breakage of the strain generating body 50 and the strain
gauge 60.

[0080] That is, according to the embodiment, the side face 21 of the
opening 20 is simply configured to be the vertical surface, thereby the
improvement of the seating detection ability to the small load is
compatible with the breakage prevention of the strain generating body 50
and the strain gauge 60 due to the excessive load.

[0081] Without providing the position shift absorption member 30, the
shaft portion 17 may be configured to push directly the strain generating
body 50. However, like the embodiment, if the load of the shaft portion
17 is set to receive by the position shift absorption member 30 once, the
position shift absorption member 30 can absorbs the position shift of the
toilet seat 15.

[0082] Since an area of the load receiver 35 of the position shift
absorption member 30 is broader than an area of the shaft portion 17
contacting the load receiver 35, even though the position of the shaft
portion 17 shifts by movement of the user during seating, the load
receiver 35 can receive surely the load due to seating of the user.
Furthermore, an area of the push portion 36 pushing the strain generating
portion 50 is smaller than the area of the load receiver 35, even though
the shaft portion 17 shifts, the shift of the position due to the strain
generating body 50 pushed by the push portion 36 is suppressed, and the
position shift of the shaft portion 17 does not influence the deflection
of the strain generating body 50.

[0083] That is, even if the position where the shaft portion 17 contacts
the load receiver 35 varies, the load in the vertical direction is
transmitted to a specified region of the strain generating body 50 from
the push portion 36 independently on the contact position of the shaft
portion 17. The deflection (strain amount) of the strain generating body
50 is not influenced by the position of the shaft portion 17, but depends
on the magnitude of the load in the vertical direction.

[0084] In the case where without providing the position shift absorption
member 30, the shaft portion 17 is configured to push directly the strain
generating body 50, for example, there is a possibility that if the
contact position of the shaft portion 17 shifts toward the end from the
center portion of the strain generating body 50, the strain generating
body 50 cannot deflect sufficiently and the strain amount necessary for
detection may not be detected.

[0085] In contrast, if the position shift absorption member 30 is
provided, also in the case where the shaft portion 17 is located on the
center portion of the strain generating body 50 and in the case where the
shaft portion 17 is located toward the end of the strain generating body
50, the push portion 36 pushes the same specified region of the strain
generating body 50, the strain generating body 50 deflects in a similar
way, and the strain amount detected by the strain gauge 60 becomes the
same as well. Even if the user moves during seating and the shaft portion
17 shifts toward the end of the strain generating body 50, the deflection
(strain) necessary for seating detection can be generated in the strain
generating body 50, and it is possible to detect surely seating of the
user on the toilet seat 15.

[0086] FIGS. 12A to 12C are schematic views showing other examples of the
opening formed in the casing 11 and having the shaft portion 17 of the
toilet seat 15 inserted.

[0087] A side face 121 of an opening 120 shown in FIG. 12A is not a
vertical surface but a curved surface. A curvature of the side face 121
is smaller than a curvature of a surface on an upper side and a curvature
of a surface on a lower side of the opening 120. Even if the side face
121 where the shaft portion 17 is capable of abutting is a curved
surface, if the curvature is small, the magnitude of the force converted
in the vertical direction when the shaft portion 17 abuts the side face
121 can be small. Even if the side face of the opening is not a perfect
vertical surface and has a slight curvature, it is sufficient as long as
an increase/decrease width to the original vertical load applied to the
strain generating body 50 can be suppressed within a range that does not
influence the seating detection and the breakdown load of the strain
generating body 50.

[0088] From such a standpoint, an inclination angle .theta. of the side
face 121 from the vertical direction is preferable to be not more than
10.degree., further preferable to be not more than 5.degree.. The 0
represents the inclination angle from the vertical direction (dotted
line) of a line approximated by a straight line of the side face 121
indicated as a curved surface in a plan view of the opening 120 or a
tangential line at an arbitrary point.

[0089] It is sufficient that a shape (contour) of the opening is rotatable
in as state in which the shaft portion 17 is inserted into the opening.
For example, as shown in FIG. 12B, it may be a rectangular opening 220.
The opening 220 has a side face 221 which is a vertical surface as well
as the opening 20 of the above embodiment, furthermore a surface on an
upper side and a surface on a lower side are continuous planar surfaces
forming a right angle to a side face 221.

[0090] Like an opening 320 shown in FIG. 12C, a side face 321 may be a
curved surface becoming a mountain toward the inside the opening 320.
Also in this case, as described previously, the inclination angle .theta.
from the vertical direction of the side face 321 is preferable to be not
more than 10.degree., furthermore preferable to be not more than
5.degree..

[0091] FIG. 13A is a schematic cross sectional view along a vertical
direction of a hinge portion of other embodiment, and FIG. 13B is a
partial cross sectional side view as viewing a left side to a D-D line in
FIG. 13A.

[0092] In the hinge portion as shown in FIGS. 13A and 13B, a shaft portion
151 is provided in a casing 150, and an opening 170 into which the shaft
portion 151 is inserted is formed on the toilet seat 15 side.

[0093] The toilet seat 15 includes the toilet seat main part 16 shown in
FIG. 1A and a hollow shaft portion 160 shown in FIG. 13A, and the toilet
seat main part 16 is combined with the hollow shaft portion 160. The
opening 170 is formed in the hollow shaft portion 160, and the shaft
portion 151 of the casing 150 is inserted into the opening 170.

[0094] The hollow shaft portion 160 is rotatable around the shaft portion
151, and consequently the toilet seat 15 rotates using the shaft portion
151 of the casing 150 as a fulcrum.

[0095] The strain generating body 50 is held on an inner wall of the
hollow shaft portion 160 on the toilet seat side. The strain gauge 60 is
provided on the upper surface of the strain generating body 50. The
strain generating body 50 is provided above the shaft portion of the
casing 150, and the position shift absorption member 30 is provided
between the strain generating body 50 and the shaft portion 151.

[0096] The hollow shaft portion 160 of the toilet seat 15 holding the
strain generating body 50 is on the shaft portion 151 of the casing 150
via the position shift absorption member 30. That is, the shaft portion
151 of the casing 150 receives the vertically downward load of the toilet
seat 15 via the position shift absorption member 30, and generates the
strain in the strain generating body 50. The strain amount of the strain
generating body 50 is detected by the strain gauge 60.

[0097] Due to the movement of the toilet seat 15 in the front-back
direction (horizontal direction in FIG. 13B), the hollow shaft portion
160 of the toilet seat 15 moves in the front-back direction, and the
shaft portion 151 of the casing 150 is capable of abutting a side face
171 of the opening 170.

[0098] As shown in FIG. 13B, the side face 171 of the opening 170 is a
vertical surface. For that reason, as described previously, even if the
shaft portion 151 abuts the side face (vertical surface) 171 of the
opening 170, the load in the horizontal direction is not converted to the
load in the vertical direction. Therefore, since the load applied to the
strain generating body 50 in the vertical direction when the user seats
on the toilet seat 15 is not influenced by the load due to the weight
shift or the like of the user in the front-back direction, and the
original vertical load is applied surely to the strain generating body
50, it is possible to detect surely seating of the user on the toilet
seat 15. Since the vertical load converted to the horizontal load is not
transmitted to the strain generating body 50, the excessive load is not
applied to the strain generating body 50 and it is possible to prevent
the breakage of the strain generating body 50 and the strain gauge 60.

[0099] The embodiments of the invention have been described with reference
to the specific example. However, the invention is not limited thereto.
Various variations are possible on the basis of the technical idea of the
invention.